

Thomas wasn't originally based on a prototype rather, the initial stories were an accompaniment to the toy made for Christopher. This engine looked rather different from the character in the books and television series, and carried the letters NW on its side tanks, which stood for "No Where" according to Awdry. When Awdry created Thomas, the engine existed only as a wooden toy made for his son Christopher. The TV series and Hornby based Thomas on this prototype belonging to the LB&SCR E2 class The programme became an award-winning hit around the world, with a vast range of spin-off commercial products. In 1979, British writer and producer Britt Allcroft came across the books, and arranged a deal to bring the stories to life as the TV series Thomas the Tank Engine & Friends (later simplified to Thomas & Friends). Later episodes of Thomas & Friends have Thomas in a trio with James and Percy, and Percy is known as his best friend. In The Railway Series and early episodes of Thomas & Friends, Thomas's best friends are Percy and Toby, though he is also close friends with Edward.

Thomas first appeared in 1946 in the second book in the series, Thomas the Tank Engine, and was the focus of the four short stories contained within.

All of the vehicles in The Railway Series were based on prototypical engines Thomas's basis is the LB&SCR E2 class. Thomas is a blue steam engine and has a number 1 painted on his side. He became the most popular and famous character in the series, and is the titular protagonist in the accompanying television adaptation series Thomas & Friends and its reboot Thomas & Friends: All Engines Go. Thomas the Tank Engine is an anthropomorphised fictional tank locomotive in the British Railway Series books by Wilbert Awdry and his son, Christopher, published from 1945.
